This invention relates to stoves and furnaces, and, more particularly, to a maximum efficiency stove or furnace especially adapted for burning wood and other solid fuels including a primary combustion area for burning a primary fuel and secondary combustion areas for further combusting the gases of combustion which leave the primary combustion area.
Stoves and furnaces for burning wood and other solid fuels have long been known. Many, if not most, of the prior known stoves and furnaces are designed principally to burn only the primary wood or other fuel in order to heat surrounding air and provide warmth in a home or other building. With fire wood, it is known that only 40 percent of the heat value or BTU content of a quantity of wood fuel is obtained by the primary burning of that fuel. Approximately 60 percent of the heat value or BTU's remain in the gases of combustion which escape through an exhaust or chimney. Many, if not most, of the prior known structures provide no method for extracting that remaining 60 percent of the heat value and transferring that heat to the surrounding air. Such stoves do not provide any secondary combustion of the primary combustion gases and, therefore, operate at a severely reduced efficiency based on the quantum of heat actually present in the fuel being burned.
A related problem in many prior known stoves or furnaces is the lack of proper draft control of air utilized to sustain combustion. Even if apparatus is included for at least partially burning the gases of primary combustion, a critical problem results if air utilized to sustain either the primary or secondary combustion is not adequately controlled. Thus, too great a quantity of primary combustion air and too little secondary combustion air creates an overly hot primary burn without sufficient air or oxygen to sustain the secondary combustion. Conversely, too little primary combustion air and too great an amount of secondary combustion air creates a low temperature primary burn and little or no secondary combustion.
Another problem is that of blending and mixing air or oxygen necessary to sustain either primary or secondary combustion. Such air must be introduced into the primary or secondary combustion areas at a temperature which enhances and does not detract from combustion in either area. Further, prior stoves have not introduced such fresh air into the combustion area at the proper locations for efficient burning.
Prior known stoves or furnaces have also provided generally inefficient methods of heating ambient or surrounding room air and transferring heat from the process of combustion to that air. Even if sufficient combustion of a fuel is obtained, heat transferred to the air in the vicinity of the combustion area is often inadequate.
Other related problems with the operation of stoves or furnaces include the inability to properly humidify or add moisture to the heated air to prevent discomfort from the dryness which results from such heating.